Various methods and systems are available for collecting three-dimensional data for digitization of a three-dimensional object. This data can be obtained from non-contact devices such as laser scanners or camera-based Moire interferometry systems.
Laser scanning is a light mensuration technique which has been used to collect data from the surface of a three-dimensional article. The data points correspond to coordinate values over the surface of the scanned article, for example taken along the X, Y and Z axes. The laser scan head traverses a scan path over the surface of the article and at selectable distances along the path, point values may be taken. The laser scan generally results in generation of a set of scan data in a digitized format. The Hunter U.S. Pat. No. 5,552,992 and the Dehoff et al. U.S. Pat. No. 5,452,219 disclose such a technique.
The Cline et al. U.S. Pat. No. 4,525,858 discloses a method and apparatus for reconstruction of three-dimensional surfaces from interference fringes wherein the three-dimensional surface is used as input to a CAD/CAM system.
The Ebenstein et al. U.S. Pat. No. 5,414,647, Kiridena et al. U.S. Pat. No. 5,546,328, Ebenstein U.S. Pat. No. 5,384,717, Kiridena et al. U.S. Pat. No. 5,442,572, and Ebenstein U.S. Pat. No. 5,319,567 all disclose the use of a laser scanner to collect three-dimensional point data of a part surface to thereby obtain a high density point data model. The high density point data model does not approximate part geometry like a traditional CAD model does where a relatively few number of points are used to represent a part by using these points as control points in constructing spline curves or other mathematical curves to represent part geometry. If one requires a better geometric definition of the high density point data model, one only need take the data at a higher density or use a more accurate measuring device to get more accurate data.
With particular reference to the Ebenstein et al. U.S. Pat. No. 5,414,647, the patent acknowledges the problem of integrating high density data scans which have been collected from different orientations. The patent describes the use of the location of reference features in local coordinate systems to obtain a transform and mapping scan data from the local coordinate systems into a global coordinate system based on the transform to obtain a CAD model of the object in the global coordinate system. However, oftentimes it is difficult, if not impossible, to determine or provide for reference features in the local coordinate systems.
The Raab U.S. Pat. Nos. 5,402,582, 5,412,880, and 5,510,977 disclose a portable coordinate measuring machine comprising a multi-jointed manually positionable measuring arm for measuring a volume including a controller which acts as an electronic interface between the arm and a host computer.
The Batchelder U.S. Pat. Nos. 5,491,643 and 5,426,722 and the Crump U.S. Pat. Nos. 5,340,433 and 5,121,329, and the Crump et al. U.S. Pat. No. 5,503,785 all disclose a rapid prototyping system in the form of a fused deposition modeling system which builds a model layer-upon-layer using an extrusion and laminating procedure from a CAD model of a part.